Bringing In the Righty. And the Lefty.

Nearly 20 years ago Greg Harris, a journeyman reliever, finally fulfilled his dream to pitch with each hand in a major league game. In the ninth inning of a loss to the Cincinnati Reds on Sept. 28, 1995, Harris, then with the Montreal Expos, came into the game as a right-hander and retired Reggie Sanders on his first pitch. He switched to his left arm to walk Hal Morris and retire Eddie Taubensee, then was back to his right to induce a groundout from Bret Boone.

Harris’s ability to exploit matchup advantages might have seemed revolutionary, but the experiment did not last long. He pitched in just one other game, using only his right hand, then retired having thrown 1,466 innings as a right-hander and one as the modern era’s first switch-pitcher. (Harris was also a switch-hitter.)

With Friday’s call-up of Pat Venditte by the Oakland Athletics, baseball has its second switch-pitcher.

In his eighth professional season, Venditte turns 30 this month and stretches the definition of the word prospect, but he has proved effective in the minor leagues, compiling a 2.37 E.R.A. for his career and striking out an impressive 10 batters per nine innings pitched. His numbers should be taken with a grain of salt; he has often been far older than his competition — including this season, when he was 3.1 years older than the average pitcher in the Pacific Coast League. But as a long reliever who can adapt to whichever side a batter hits from, he may provide some versatility in the Oakland bullpen.

Venditte got off to a good start Friday, switch-pitching two scoreless innings against Boston.

Given the various strategies tried over the years in hopes of gaining an advantage, the scarcity of switch-pitching is somewhat surprising, making a case that mastering pitching with each hand is truly a rare skill, and rendering Venditte’s effectiveness from both sides even more remarkable. This season, in 192/3 innings as a right-hander, he held opponents to a .208 batting average. In 131/3 innings as a left-hander, he was even better, holding them to .095. Last season, in 26 appearances for the Yankees’ Class AAA Scranton/Wilkes-Barre affiliate, Venditte allowed a .250 batting average with each arm.

For an MLB.com article in 2000, Jerome Holtzman, the longtime Chicago sports columnist and former official Major League Baseball historian, found several instances of switch-pitching, with the most recent one before Harris coming in 1893. But other pitchers, including Tug McGraw with the Mets, reportedly lobbied to try it in a regular-season game.

In his first appearance, Venditte was able to give a brief demonstration of Rule 5.07(f), which requires a switch-pitcher to declare which arm he will use before a batter steps to the plate. The rule was meant to avoid a standoff with the pitcher and the hitter refusing to pick sides. With the switch-hitting Blake Swihart approaching the plate as a right-handed batter, Venditte indicated he would pitch with his right hand, and Swihart went back to the dugout for his lefty-hitting helmet.

Having joined Harris in the record book as a modern switch-pitcher, Venditte now gets a chance to prove that the strategy can be sustainable.

A version of this article appears in print on , on Page D7 of the New York edition with the headline: Bringing in the Righty. and the Lefty.. Order Reprints | Today’s Paper | Subscribe